All Tables

Table 1: Summary of HESS observations of RX J1713.7-3946 conducted during three years. For each year, the targeted position is given together with the wobble offsets in Right Ascension $(\alpha _{\rm J2000})$ and Declination $(\delta _{\rm J2000})$ . Adding the wobble offsets to the target coordinates, the actual pointing position is obtained. For each pointing position, the dead-time corrected observation time (Live time) is given in hours. Data recorded under bad weather conditions are excluded. The columns Data set I-III summarise observation times of data sub-sets used throughout the paper. Data set I is used for Fig. 2; to obtain optimum angular resolution, the 2003 data are disregarded and a zenith-angle cut at $60\hbox {$^\circ $ }$ is applied (the latter is only relevant for the 2005 data). Data set II is used for spectral comparisons of the different years (cf. Fig. 3). Observations with wobble offsets of $0\hbox {$^\circ $ }$ in 2004 and 2005 are disregarded for this purpose. Data set III comprises all data, and is used for the generation of the combined spectrum (cf. Fig. 4).
Table 2: Summarised are the event statistics of the whole SNR and corresponding angular resolutions for the years 2003, 2004, and 2005. The 2004 and 2005 data sets correspond to Data set I of Table 1. The average zenith angle $\langle \phi_{z} \rangle$ is determined from all events reconstructed in the SNR region. For the angular resolution (R₆₈), the 68% containment radius of the simulated gamma-ray point-spread function, matched to the particular data set, is used as figure of merit. The other columns give the number of signal events from the SNR region (ON), the number of background events (OFF), the normalisation factor between ON and OFF counts ( $\alpha$ ), and the corresponding significance and live observation time. $\alpha$ is in general defined as the ratio of the effective exposure integrated in time and angular space of the ON and OFF region. Note that the analysis of the 2003 data is adopted to match the system configuration of this year. The nominal analysis is applied for the 2004 and 2005 data. For 2005, only data recorded at zenith angles less than $60\hbox {$^\circ $ }$ are included (therefore the mean zenith angle decreases). The event statistics are determined with the ON/OFF approach for 2003 and the reflected-region method for 2004 and 2005. In the latter two years, also ON runs with wobble offsets < $0.7\hbox {$^\circ $ }$ (cf. Table 1) are included and hence $\alpha >1$ .
Table 3: Comparison of event statistics from the SNR region from three years of data. The numbers result from the spectral analysis of Data set II (cf. Table 1), shown in Fig. 3. Given are the number of signal (ON) and background (OFF) counts, the normalisation factor $\alpha$ , the statistical significance of the gamma-ray excess ( $\sigma$ ) and the observation time. For the 2003 data, the special two-telescope analysis with a cut on the minimum size of camera images at 300 photo-electrons was applied. The background estimate in this case is derived with the ON/OFF analysis. For 2004 and 2005, the nominal spectral analysis with a cut at 80 photo-electrons was used together with reflected-region background model.
Table 4: Fit results for different spectral models. The fit range is chosen from 0.3 to 113 TeV. The differential flux normalisation I₀ is given in units of $10^{-12} ~ {\rm cm}^{-2} ~ {\rm s}^{-1} ~ {\rm TeV}^{-1}$ . Shown are a power-law model (row 1), a power law with an exponential cutoff (row 2, 3, 4; the cutoff energy $E_{\rm c}$ is given in TeV), a power law with an energy dependent photon index (row 5), and a broken power law (row 6; in the formula, the parameter S = 0.6 describes the sharpness of the transition from $\Gamma _1$ to $\Gamma _2$ and it is fixed in the fit). Note that when fitting a broken power law to the data, some of the fit parameters are highly correlated.
Table 5: Flux points including relevant event statistics are listed for the spectrum of the combined HESS data set, shown in Fig. 4. For all 28 bins, the energy, the number of signal and background counts (ON and OFF), the normalisation factor $\alpha$ , the statistical significance $\sigma$ , the gamma-ray flux and the energy range of the bin are given. The significance is calculated following Li & Ma (1983). For the final bin, as it has only marginally positive significance, we list both the actual flux point and the $2\sigma$ upper limit (which is drawn in Fig. 4). Note that the energy and flux values given here are corrected for the variation of optical efficiency, as discussed in the main text.